In this type of circuit breaker, the permanent moving contact through which the permanent current flows is generally a copper tube of relatively large mass which, during a circuit-breaking operation, is driven at high speed in conjunction with an arcing contact. A large amount of energy is required for this operation since the energy requirement is proportional to the product of the mass of the moving equipment multiplied by the square of the speed at which the equipment is displaced. All manufacturers seek to reduce this operating energy since its large size penalizes the cost of the equipment for operating the circuit breaking device.
An object of the invention is to provide a circuit breaker in which both the mass and the displacement speed of the moving contact during a circuit-breaking operation are reduced compared with a prior art contact, while nevertheless maintaining a high displacement speed for the arcing contacts.
This result is obtained by disuniting the moving main contact from the moving equipment and by implementing the moving main contact as a short element associated with displacement means communicating a speed thereto during a circuit breaking operation which is less than the speed of said moving equipment.